ANKARA, Turkey — Turkey’s interior affairs minister has offered his resignation to Prime Minister Recep Tayyip Erdogan over a massive corruption and bribery scandal that has resulted in the arrest of his son and 23 other people.

The Turkish leader, however, again dismissed the scandal Sunday as a shadowy international plot against his government, while Turkish authorities pressed ahead with a purge of the police officials allegedly investigating the case.

Twenty-four people — including Interior Minister Muammer Guler’s son, the son of Economy Minister Zafer Caglayan and the head of the state-owned Halkbank — have been arrested and accused of taking or facilitating bribes. Newspaper reports say police seized millions of dollars in cash stashed in shoe boxes from the bank chief’s home.

The probe poses a strong challenge to Erdogan’s long-time Islamic-led government, which weathered a wave of nationwide protests against its rule this summer.

In an interview with the state-run Anadolu Agency, Guler denied any wrongdoing and said there was “nothing I cannot account for.”

He had offered to resign and told the Turkish leader he was “prepared to be sacked” by him, and was awaiting his decision on the issue, Guler said.

Erdogan was already expected to reshuffle his Cabinet this week to replace three ministers who are running for mayoral posts during local elections set for March. Reports said he would expand the Cabinet changes to include Guler and other ministers implicated in the scandal.

Police in Istanbul on Sunday clashed with a group of protesters denouncing the scandal, firing water canons and tear gas at a group who hurled rocks at them, the Dogan news agency reported. Hundreds of people took part in the demonstration.

Turkish commentators say the investigation and the arrests are the result of a power struggle between Erdogan’s government and an influential Islamic movement led by the U.S.-based cleric Fethullah Gulen, which is widely believed to hold sway within Turkey’s police and judiciary.

Some 25 police chiefs were removed from senior positions at the Istanbul police headquarters, the Anadolu Agency reported Sunday, in addition to dozens of others dismissed from posts since the probe was launched earlier in the week. Analysts said the dismissals were a government attempt to purge the police force of Gulen’s followers.

Opposition parties have accused Erdogan of trying to whitewash the scandal.